# Reaction rates

Notes on reaction rates

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Rates of reaction
A reaction occurs when a particle exceeds the activation energy for the
reaction. The activation energy of a reaction is not fixed; it can be changed
using a catalyst or a higher temperature.
The rate of reaction is determined by two different values, the rate
products are used up at and the rate products are produced at.
There is a simple equation for working out rate of reaction
Rate = Change in concentration / Time
So let's say we perform a test with C + O2 and the concentration of CO2
changes by 10 moles per decimetre cubed in 10 seconds, put this into the
equation and your rate is 1 mol per decimetre cubed per second, this is the
unit for rate of reaction.
Finding the rate from experimental results
The rate of reaction is the gradient of the curve / time. This is simple but
calculating the gradient is more difficult,
1. Draw a tangent (look it up) from the point on the line you are measuring
the change at
2. Draw a horizontal line across to another point on the curve, say 10 seconds
from the point you are measuring from, this would make the time 10.
3. Divide the amount of squares the tangent goes down by the amount is goes
across; this is the rate